Estimate the cash and store-credit totals for a basket of items to sell, plus free-shipping eligibility and whether it routes to a personal review. Estimate only — no quote is persisted. Provide each item's buyPrice from lookup_market_price.
Part of the NOSTOS server.
Free to start. No card required.
AI agents call get_trade_in_offer_estimate to retrieve information from NOSTOS without modifying any data. This is common in research, monitoring, and reporting workflows where the agent needs context before taking action. Because read operations don't change state, they are generally safe to allow without restrictions -- but you may still want rate limits to control API costs.
Even though get_trade_in_offer_estimate only reads data, uncontrolled read access can leak sensitive information or rack up API costs. An agent caught in a retry loop could make thousands of calls per minute. A rate limit gives you a safety net without blocking legitimate use.
Read-only tools are safe to allow by default. No rate limit needed unless you want to control costs.
{
"version": "1",
"default": "deny",
"tools": {
"get_trade_in_offer_estimate": {}
}
}See the full NOSTOS policy for all 14 tools.
These attack patterns abuse exactly the kind of access get_trade_in_offer_estimate gives an agent. Each links to the full case and the policy that stops it:
Other read tools across the catalogue. The same approach applies to each: allow, with a rate cap to control cost.
Estimate the cash and store-credit totals for a basket of items to sell, plus free-shipping eligibility and whether it routes to a personal review. Estimate only — no quote is persisted. Provide each item's buyPrice from lookup_market_price.. It is categorised as a Read tool in the NOSTOS MCP Server, which means it retrieves data without modifying state.
Register the NOSTOS MCP server in PolicyLayer and add a rule for get_trade_in_offer_estimate: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches NOSTOS. Nothing to install.
get_trade_in_offer_estimate is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the get_trade_in_offer_estimate rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for get_trade_in_offer_estimate. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
get_trade_in_offer_estimate is provided by the NOSTOS MCP server (https://mcp.nostos.market/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 14 NOSTOS tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
4,600+ MCP servers and 31,000+ tools scanned and risk-classified.